Submersed heat exchanger

ABSTRACT

Systems and methods for transporting a hydrocarbon are provided. The method can include introducing a fluid at a first pressure and a first temperature to an inlet of a pump and pressurizing the fluid within the pump to produce a pressurized fluid having a second pressure and a second temperature. The method can also include flowing at least a portion of the pressurized fluid through a first heat exchanger and back to the inlet of the pump. The heat exchanger can include a coil having an inlet and an outlet and a housing at least partially enclosing the coil and having a first opening and a second opening. A first end of the coil can be disposed proximate the first opening. The heat exchanger can also include a foundation for supporting the coil and the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/981,824, Titled “Submersible Heat Exchanger,” filed on Dec. 30, 2010,the contents of which are incorporated by reference for all purposes.

BACKGROUND

Field

Embodiments described herein generally relate to processing ahydrocarbon. More particularly, such embodiments relate to subseahydrocarbon production.

Description of the Related Art

Low flow rate conditions can occur in subsea hydrocarbon productionrequiring artificial lift techniques to bring the hydrocarbons to thesurface, both in new production, referred to as “green fields,” andduring reservoir maintenance, referred to as “brown fields.” Manifoldsand flow lines used in these production techniques have a maximum designtemperature, and pumps used to create artificial lift can have a limitedrange of flow rate capacity. Often pumps placed at or near productionzones are designed in view of maximum flow rates and can only be turneddown to about 80% of their maximum efficiency. Recirculation loopsaround pumps can be used to increase the operational envelope of thepump and can lower the acceptable minimum flow rate from a field orwell. If the pressurized hydrocarbon is recycled using a recirculationloop, however, temperature in the system can increase exponentially, andquickly surpass the maximum design temperature of the flow lines,manifolds, and/or pump.

To counteract such temperature increase, seawater, in subsea hydrocarbonproduction, can be used as a coolant. The pipe, for example, can bearranged with one or more bends to increase the contact area between thepipe and the seawater. This approach is dependent on the watertemperature and native currents in the seawater.

There is a need, therefore, for new apparatus and methods forcontrolling the temperature of a pumped and/or boosted fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a perspective sectional view of an illustrative heatexchanger, according to one or more embodiments described.

FIG. 2 depicts a perspective sectional view of an illustrative heatexchanger having a second sliding sleeve, according to one or moreembodiments described.

FIG. 3 depicts a schematic of an illustrative system for controlling thetemperature of a fluid during transport having the heat exchangerdepicted in FIG. 1, according to one or more embodiments described.

FIG. 4 depicts a schematic of another illustrative system forcontrolling the temperature of a fluid during transport having two ofthe heat exchangers depicted in FIG. 1 arranged in series with respectto one another, according to one or more embodiments described.

FIG. 5 depicts a schematic of yet another illustrative system forcontrolling the temperature of a fluid during transport having two ofthe heat exchangers depicted in FIG. 1 arranged in parallel with respectto one another, according to one or more embodiments described.

DETAILED DESCRIPTION

Systems and methods for transporting a hydrocarbon are provided. Themethod can include introducing a fluid at a first pressure and a firsttemperature to an inlet of a pump and pressurizing the fluid within thepump to produce a pressurized fluid having a second pressure and asecond temperature. The method can also include flowing at least aportion of the pressurized fluid through a first heat exchanger and backto the inlet of the pump. The heat exchanger can include a coil havingan inlet and an outlet and a housing at least partially enclosing thecoil and having a first opening and a second opening. A first end of thecoil can be disposed proximate the first opening. The heat exchanger canalso include a foundation for supporting the coil and the housing.

FIG. 1 depicts a perspective sectional view of an illustrative heatexchanger 100, according to one or more embodiments. The heat exchanger100 can include one or more coils 110, housings 115, and foundations orbases 160. The coil 110 can have an inlet 105 for receiving fluid, e.g.,a hydrocarbon, and can have an outlet 106 for transmitting the fluid,e.g., a cooled or heated hydrocarbon. The coil 110 can have a first or“bottom” end 113 and a second or “top” end 112. The coil 110 can includeone or more conduits 114. The inlet 105 can be in fluid communicationwith the second end 112 of the coil 110 and the outlet 106 can be influid communication with the first end 113 of the coil 110. A flow valve136 can be disposed on the inlet 105 to adjust a flow of the fluidthrough the coil 110.

As used herein, the terms “up” and “down;” “upward” and “downward;”“upper” and “lower;” “upwardly” and “downwardly;” “above” and “below;”and other like terms refer to relative positions to one another and arenot intended to denote a particular spatial orientation since theapparatus and methods of using the same can be equally effective atvarious angles or orientations.

The conduits 114 of the coil 110 can have a variety of shapes and sizes.For example, the cross sectional shape of the conduits 114 can be, butis not limited to, circular, elliptical, oval, triangular, rectangular,square, polygonal, some other geometric shape, or any combinationthereof. The conduits 114 can be formed in a straight line, in a loop orseries of loops, in a series of bends, along a serpentine or “zigzag”path, or any combination thereof. For example, the coil 110 can have asubstantially straight inlet conduit 111, as shown, that can connect theinlet 105 to the second end 112 of the coil 110, and the one or moreconduits 114 can be formed in a helical or coiled arrangement from thesecond end 112 to the first end 113 of the coil 110. The conduits 114can include features to improve heat transfer effectiveness of the coil110, including, but not limited to, increased surface area (e.g., finsand/or flattened pipes), material with a high heat transfer coefficient,thinner tube walls, or any combination thereof.

The inlet conduit 111 can connect the inlet 105 to the second end 112,i.e., the “top” of the coil 110. Connecting the inlet conduit 111 to thesecond end 112 of the coil can reduce or minimize a change intemperature from the inlet 105 to the external environment and canproduce a counter current flow of a fluid flowing through the coil 110with respect to a convection current flowing outside the coil 110. Asmaller change in temperature can reduce or minimize scaling on the coil110. Although not shown, the inlet conduit 111 can connect the inlet 105to the side or bottom of the coil 110 to provide parallel flow heatexchange. When the heat exchanger 100 operates to cool a fluid flowingthrough the coil 110, the fluid introduced to the second end 112 of thecoil 110 can be at a greater temperature than the fluid within the coil110 at the first end 113.

The coil 110 can be designed to operate in subsea conditions. Forexample, the coil 110 can include a brass plating, e.g., navy brassand/or can be at least partially covered or coated with one or moreanti-fouling agents to help prevent damage to the coil 110 caused byscaling, mineral deposits, and/or marine growth. The coil 110 can becomposed in whole or in part, of one or more metals, metal alloys, orany combination thereof. For example, the coil 110 can be composed ofcarbon steel in whole or in part. In another example, the coil 110 canbe composed of from about 5 mm to about 10 mm thick carbon steel tubingor piping. In another example, the coil 110 can be composed of about 6mm (about 0.25 inches) steel tubing or piping.

The housing 115 can at least partially enclose the coil 110 and can haveone or more first openings 117 and one or more second openings 118. Thefirst end 113 of the coil 110 can be disposed proximate the firstopening 117 and the second end 112 of the coil 110 can be orientedtoward the second opening 118. The housing 115 can include one or moresidewalls 116 and a frame 125. The housing 115 can mitigate influenceson the coil 110 from the environment, e.g., subsea currents and cancreate stability for heat transfer. When the heat exchanger 100 operatesto cool a fluid flowing through the coil 110, the heat transfer mediumcan flow through the first opening 117 and out the second opening 118.

The coil 110 can be disposed within the housing 115 and spaced from thesidewall 116 and the frame 125. For example, the coil 110 can becentered within the housing 115. The space or distance between the coil110 and the sidewall 116 can, among other factors, help induce a currentof a heat transfer medium or coolant, e.g., water or seawater, withinthe housing 115.

The frame 125 and the sidewall 116 can provide strength and/or shape tothe heat exchanger 100. For example, the frame 125 can reinforce thesidewall 116. The frame 125 can have a variety of shapes and sizes toallow inflow and outflow of the heat transfer medium into and out of theheat exchanger 100. For example, the frame 125 can be shaped as, but isnot limited to, a cube, a rectangular box, a cylinder, a cone, a sphere,a dome, a pyramid, a polyhedron, a triangular prism, a hyperboloidstructure, or some other shape or combination thereof. As shown, theframe 125 can have a cylindrical bottom and a dome shaped top, wherepoles or bars 126 can be substantially perpendicularly disposed on,attached to, or otherwise secured to the foundation 160 for addedsupport. A cylindrical bottom and dome shaped top can be easilymanufactured, structurally sound, and/or can handle stresses ofexpansion and/or contraction.

The top of the frame 125 can have one or more openings sized to allowtooling, e.g., cleaning tools, to reach the coil 110 and other parts ofthe heat exchanger 100. For example, the frame 125 can protrude from thesecond opening 118 of the housing 115, leaving openings between thepoles 126. The openings between the poles 126 and the second opening 118of the housing 115 can be used as maintenance ports. In another example,the poles 126 can be joined to a ring 127 to form the domed shaped topof the frame 125. The ring 127 can be aligned along a longitudinal axis,e.g., a central longitudinal axis, extending through the second opening118 of the housing 115. Tools and/or control lines (not shown) can beintroduced to the coil 110 via the ring 127. For example, a highpressure jet (not shown) can be lowered through the ring 127 and alignedtherewith, to clean the inside of the housing 115 and/or the coil 110.The ring 127, in conjunction with the rest of the frame 125, can be usedfor alignment and stability of the heat exchanger 100 while it is movingand/or while it is stationary. For example, the frame 125 can providesupport for the heat exchanger 100 if it is being moved to or removedfrom its operating location, e.g., the sea floor bottom proximate awellbore or production zone. Various equipment and tools can connect tothe frame 125 during movement of the heat exchanger 100 and/or duringmaintenance of the heat exchanger 100.

Although not shown, the top of the frame 125 can be partially orcompletely enclosed by a cover. The cover (not shown) can be removableor can have access ports disposed therein. The cover can be or include ascreen that can allow fluid transfer and protect the heat exchanger 100from debris and projectiles.

The sidewall 116 of the housing 115 can be disposed on the outsideand/or inside of the frame 125, can be formed as part of the frame 125,or a combination thereof. In one example, the frame 125 and the sidewall116 can be integrated with one another, i.e., one piece. The sidewall116 can match or correspond to the shape of the frame 125 or can have adifferent shape. For example, if the bottom of the frame 125 iscylindrical, as shown, the sidewall 116 can have a similar cylindricalshape. Although not shown, the sidewall 116 can have a different shapethan frame 125. For example, the sidewall 116 can be boxlike if theframe 125 is cylindrical.

The sidewall 116 can extend from the first opening 117 to the secondopening 118. The sidewall 116 can minimize or reduce dynamic changesbased on external surroundings. For example, the sidewall 116 canprotect the coil 110 from damage caused by projectiles, nearbyequipment, currents, and/or erosion. The sidewall 116 can be designedwith vibration limiting and/or drag reducing devices including, but notlimited too, fins, fairings, and strakes. Although not shown, thesidewall 116 can have doors and/or baffles to further control currentflow through the coil 110. Doors (not shown) in the sidewall 116 can beused as maintenance ports for maintenance and/or installation ofcomponents of the coil 110.

The sidewall 116 can help to mitigate, control, or adjust a current orflow rate of the heat transfer medium. For example, the larger adistance 119 between the second end 112 of the coil 110 and the secondopening 118, the less effect current can have on an efficiency of theheat exchanger 100. The distance 119 for a given heat exchanger 100 canbe based, at least in part, on an appropriate distance that can maximizeheat transfer between the heat transfer medium and the fluid in the coil110. The distance 119 for a given heat exchanger 100 can also be based,at least in part, on the particular location or environment. Forexample, a heat exchanger 100 located subsea in arctic waters could havea larger distance 119 than a heat exchanger located subsea in tropicalwaters. The distance 122 between the sidewall 116 and the coil 110 canalso be based, at least in part, on the size of the coil 110 and thedesired current through the heat exchanger 100. For example, depending,at least in part, on the particular environment the heat exchanger 100can be located, the distance 122 can be configured to minimize orotherwise reduce a flow rate restriction of a heat transfer medium,e.g., water or seawater, through the housing 115. Although not shown, inone or more embodiments, the distance 119 and/or the distance 122 can beadjustable or otherwise variable during operation of the heat exchanger100.

The first opening 117 can be spaced between an end of the housing 115and the foundation 160. The first opening 117 can be adjustable in size.For example, the housing 115 can include a sliding sleeve 120 that canbe adjusted to control the size of the first opening 117. The opening117 can extend or partially extend about a perimeter of the housing 115.Although not shown, the first opening 117 can be a plurality ofopenings. For example, the first opening 117 can be one or moreperforations or holes in the sidewall 116 of housing 115, the foundation160, or both. The perforations (not shown) can be adjustable in size orcan have a fixed size. For example, the perforations can be sealed orpartially sealed by removable plugs or moveable parts (not shown).

As shown, the sliding sleeve 120 can be disposed at least partiallyabout an outer surface of the sidewall 116. It will be appreciated,however, that the sliding sleeve 120 can also be disposed at leastpartially within the sidewall 116, e.g., proximate an inner surface ofthe sidewall 116. The sliding sleeve 120 can move from a closedposition, through a range of open positions, to a completely openposition. For example, the sliding sleeve 120 in the closed position canhave one end flush with the foundation 160, thereby at least partiallysealing the first opening 117. The sliding sleeve 120 can correspond inshape to the housing 115 and/or sidewall 116 to effectively extend thehousing 115 and/or sidewall 116 toward the opening 117. For example,with a cylindrical sidewall 116, the sliding sleeve 120 can becylindrical. In another example, the sliding sleeve 120 can berectangular if the housing 115 is rectangular. For a cylindrical slidingsleeve 120 and sidewall 116, the sliding sleeve 120 can have a larger orslightly larger circumference than the cylindrical sidewall 116. If thefirst opening 117 includes one or more perforations (not shown) in thesidewall 116, the sliding sleeve 120 can be in a closed position to sealthe perforations and in an open position if the perforations are atleast partially uncovered.

The sliding sleeve 120 can regulate the size of the first opening 117.For example, the degree to which the sliding sleeve 120 uncovers thefirst opening 117 can control the amount of coolant flow across the coil110. One or more motors or actuators (two are shown 140 and 141) cancontrol the movement of the sliding sleeve 120 from the closed positionto the range of open positions. The actuators 140, 141 can be controlledelectronically, pneumatically, mechanically, hydraulically, or by anycombination thereof. In one example, the sliding sleeve 120 and theactuators 140, 141 can be the only moving parts of the heat exchanger100 to limit complexity of the heat exchanger 100. In another example,the heat exchanger 100 can include other moving parts such as flowvalves 135, 136 and additional actuators (not shown).

The foundation 160 can support and/or lift the coil 110 and the housing115 from the surface, e.g., the sea floor. The foundation 160 canprevent sand and/or other debris from damaging and interfering with thefunctioning of the heat exchanger 100. The foundation 160 can supportthe housing 115. For example, the poles 126 of the housing 115 can besecured on or to the foundation 160. The foundation 160 can provide asurface on which the sliding sleeve 120 can be at least partially sealedagainst and can at least partially anchor actuators 140, 141 as theymove the sliding sleeve 120 up and down.

The foundation 160 can be any shape that can provide a stable surfacefor supporting the heat exchanger 100, including, but not limited to,cylindrical, frusto-conical, or a rectangular box. The foundation 160can vary in size as long as it is large enough to support the heatexchanger 100. The foundation 160 can be solid or be hollow, i.e.,having voids. The foundation 160, for example, can be a mudmat,manifold, concrete slab, plastic or polymeric structure such as arectangular block, rock, bricks, metal structure, or other foundationcapable of supporting the heat exchanger 100. For example, thefoundation 160 can just be a frame. Although not shown, the heatexchanger 100 can not include a foundation 160 and can sit directly onthe sea floor.

The heat exchanger 100 can include a bypass loop 107 having a first endjoined to the coil 110 proximate the inlet 105 and a second end joinedto the coil 110 proximate the outlet 106. One or more bypass valves 135can be disposed on the first end of the bypass loop 107 to allowadjustment of flow into the bypass loop 107. The bypass loop 107 and thebypass valve 135 can be disposed on the foundation 160. For example, thebypass loop 107 and bypass valve 135 can be secured to the foundation160. The bypass loop 107 can allow a coil 110 to be selectively removedor partially removed from a flow path if not in use. For example,several heat exchangers 100 can be linked in series and/or in paralleland can be selectively turned on and off by opening or closing thebypass valve 135 to the respective bypass loops 107. The bypass valve135 and the flow valve 136 can function independently or dependently toalter the flow path into or around the heat exchanger 100. For example,if the bypass valve 135 is opening to allow fluid to the bypass loop107, the flow valve 136 can simultaneously be closing to restrict flowto the coil 110. In another example, the amount of fluid introduced via105 can be reduced via the flow valve 136, the bypass valve 135, orboth.

A flow meter 130 can be disposed at or near the inlet 105. Although notshown, another flow meter can be disposed at or near the outlet 106 tomonitor flow through the heat exchanger 100. The flow meter 130 canmeasure the rate of flow coming into the heat exchanger 100 and/or thebypass loop 107.

One or more temperature sensors (two are shown 131 and 132) and one ormore pressure sensors (two are shown 133 and 134) can be disposed at orproximate the coil 110. For example, a first pressure sensor 131 and afirst temperature sensor 133 can be disposed at the inlet 105 to thecoil 110 to measure the temperature and pressure of the fluid cominginto the heat exchanger 100. A second pressure sensor 132 and a secondtemperature sensor 134 can be disposed at the outlet 106 to the coil 110to measure the temperature and pressure of the fluid coming out of theheat exchanger 100.

One or more control lines 150 can connect to the flow meter 130, thetemperature sensors 131, 133, the pressure sensors 132, 134, the bypassvalve 135, the flow valve 136, and the sliding sleeve actuators 140,141. The one or more control lines 150 can control the operation of theactuators 140, 141 and thereby the movement of the sliding sleeve 120.The one or more control lines 150 can receive signals from and/or sendsignals to a remote location (e.g., a wellbore), a controller, aboosting station, a production manifold, the surface (e.g., a surfacevessel or rig), or any combination thereof. For example, the pressuresensors 132, 134, the temperature sensors 131, 133, and/or the flowmeter 130 can communicate with other parts of a hydrocarbon coolingsystem, e.g., a pump, a control unit, and/or can communicate with thesurface.

Although not shown, a manifold can cover, contain, or otherwise at leastpartially enclose the foundation 160, the bypass line 107, the valves135, 136, the flow meter 130, and the sensors 131, 132, 133. Themanifold can also enclose one or more pumps that can function inconjunction with the heat exchanger 100. The manifold can protect thecomponents therein from environmental factors, e.g., debris, currents,and/or erosion.

In operation, the heat exchanger 100 can be partially or completelysubmersed in the heat transfer medium. Depending, at least in part, onthe particular environment the heat exchanger 100 can be located orotherwise disposed, the particular heat transfer medium can vary.Illustrative heat transfer mediums can include, but are not limited too,water, seawater, air, compressed air, mercury, hydrocarbon based fluidssuch as oil, or any combination thereof. For example, the heat exchanger100 can be disposed subsea, e.g., at a sea floor bottom at or proximatea deep sea drilling wellhead or production zone. As used herein, theterms “sea” and “subsea” are used interchangeably and can refer to anybody of water or waterway, including, but not limited to, oceans, bays,lakes, ponds, bayous, creeks, rivers, estuaries, harbors, reservoirs,brooks, lagoons, straights, streams, or any combination thereof. Inanother example, the heat exchanger 100 can be used on the surface withair as the heat transfer medium. The heat exchanger 100 can be in fluidcommunication with a wellhead or a plurality of wellheads via a manifold(not shown).

While at least partially submersed in the heat transfer medium, the coil110 of the heat exchanger 100 can receive a fluid, e.g., a hydrocarbonfluid, at the inlet 105 to produce a fluid, e.g., a cooled hydrocarbonfluid, at the outlet 106. Fluid from the inlet 105 can travel throughthe inlet conduit 111 to the second end 112 of the coil 110 and thenthrough the conduits 114 to the first end 113 of the coil 110. Heat canbe transferred from the fluid to the heat transfer medium through thewalls of the conduits 114. Heat transfer medium that has increased intemperature can rise as a result and can induce a current within thehousing 115. The heat transfer can be by conduction and/or convection.

The sidewalls 116 of the housing 115 can contain the heat transfermedium that has increased in temperature and can guide or direct theheat transfer medium toward the second opening 118 of the housing 115.To increase current flow within the housing 115, the sliding sleeve 120can be actuated from the closed position to one of its open positions toallow more heat transfer medium in through the first opening 117 of thehousing 115. For example, the flow through the housing 115 can be at amaximum flow if the sliding sleeve 120 is in its completely openposition.

The flow meter 130, the temperature sensors 131, 132, and the pressuresensors 133, 134 can measure the flow, temperature, and pressure,respectively of the fluid in going in and out of the heat exchanger 100.The information measured can be conveyed through the control line 150 orwirelessly to a control unit, the surface, or a combination thereof. Theactuators 140, 141 for the sliding sleeve 120 can be activated throughthe control line 150 or wirelessly, based, at least in part, on themeasured flow, temperature, pressure.

The actuators 140, 141 can be instructed to open the sliding sleeve 120further to allow more of the heat transfer medium to contact the coil110 if more heat transfer is desired from the heat exchanger 100.Similarly, the actuators 140, 141 can be instructed to at leastpartially close the sliding sleeve 120 to minimize or reduce the amountthe heat transfer medium contacting the coils 110. The bypass valve 135can be activated to force or allow the fluid through the bypass loop 107if the heat exchanger 100 is not required.

FIG. 2 depicts a perspective sectional view of an illustrative heatexchanger 200 having a second sliding sleeve 221, according to one ormore embodiments. The heat exchanger 200 can be similar to the heatexchanger 100, but can also have a second or “upper” sliding sleeve 221disposed proximate the second opening 118 of the housing 115.

One or more actuators (two are shown 242, 243) can raise and lower thesliding sleeve 221. The actuators 242, 243 can receive instructions viathe control line 150 or via wireless transmission. Although not shown,the actuators 242, 243 can send and receive information and/orinstructions to and/or from a remote location (e.g., a wellbore), acontroller, a boosting station, a production manifold, the surface(e.g., a surface vessel or rig), or any combination thereof.

The second sliding sleeve 221 can be adapted to change the distance fromthe second opening 118 to the coil 110. For example, the sliding sleeve221 can be raised or lowered to increase or decrease the distancebetween the second opening 118 and the second end 112 of the coil 110.As discussed and described above, the distance between the secondopening 118 and the second end 112 of the coil 110 can be designed tominimize drafting and/or current interference with the heat exchangeprocess occurring within the housing 115. The second sliding sleeve 221can allow the distance between the second opening 118 and the second end112 of the coil 110 to be adjusted for changed or changing environmentalconditions, changed or changing fluid temperature coming into the coil110, or any combination thereof. For example, if the heat exchanger 200is moved to anew location, environmental and system conditions maydiffer from a previous location. The second sliding sleeve 221 can beadjusted for those new conditions without redesign, refitting, addedcomponents, or added expense.

FIG. 3 depicts a schematic of an illustrative system 300 for controllinga temperature of a fluid during transport having the heat exchanger 100depicted in FIG. 1, according to one or more embodiments. The system 300can include one or more flow lines (two are shown 370, 385), one or morepumps 380, and one or more recirculation loops 370.

A fluid, e.g., a hydrocarbon, can be introduced via a first flow line375 to the pump 380 to produce a pumped or boosted fluid via a secondflow line 385. The pumped fluid via the second flow line 385 can betransported to an alternate location, including, but not limited to, aproduction manifold, a boosting station, the surface (e.g., a surfacevessel or rig), or any combination thereof.

One or more first temperature sensors 376, one or more first pressuresensors 377, and/or one or more first flow meters 378 can be disposed onthe first flow line 375 to measure the temperature, pressure, and flowrate, respectively, of the fluid in the first flow line 375. One or moresecond temperature sensors 381, one or more second pressure sensors 382,and one or more second flow meters 383 can be disposed on the secondflow line 385 to measure the temperature, pressure, and flow rate,respectively, of the pumped fluid in the second flow line 385. Althoughnot shown, the sensors 376, 377, 381, 382, the flow meters 378, 383, anda control valve 390 can be joined to one or more control lines. Thesensors 376, 377, 381, 382 and flow meters 378, 383 can send and receivesignals via the control lines or via wireless transmission to and fromother parts of the hydrocarbon processing operation (not shown)including, but not limited to, one or more pumps, one or more controlunits, the surface (e.g., a surface ship or rig), or any combinationthereof. Although not shown, the sensors 376, 377, 381, 382, the flowmeters 378, 383, the control valve 390, and/or the pump 380 can bedisposed in a manifold.

The fluid via the first flow line 375 can have a first temperatureranging from a low about 3° C., about 5° C., about 10° C., about 20° C.,about 30° C., or about 40° C. to a high of about 150° C., about, 175°C., about 200° C., about 225° C., about 250° C., or about 275° C. Forexample, the first temperature of the fluid via the first flow line 375can be about 15° C. to about 265° C., about 25° C. to about 230° C., orabout 35° C. to about 180° C. In another example, the first temperatureof the fluid via the first flow line 375 can be about 82° C. (about 180°F.) or less.

The fluid via the first flow line 375 can have a first pressure rangingfrom a low about 101 kilopascals (“kPa”), about 300 kPa, about 680 kPa,about 1,800 kPa, about 3,000 kPa, about 4,000 kPa, or about 5,000 kPa toa high of about 20,000 kPa, about 35,000 kPa, about 70.000 kPa, or about140,000 kPa. For example, the first pressure in the first flow line 375can range from about 25 kPa to about 125,000 kPa, about 150 kPa to about50,000 kPa, about 3,500 kPa to about 30,000 kPa. The pump 380 canincrease the pressure of the fluid introduced from the first flow line375 to maintain a flow of the fluid in the second flow line 385.

The recirculation loop 370 can have one or more heat exchangers 100disposed therein. The recirculation loop 370 can be formed by two ormore lines or conduits (two are shown 387 and 373). Fluid from thesecond flow line 385 can be introduced to the heat exchanger 100 via afirst line 387 to produce a cooled fluid via a second line 373 that canbe reintroduced to the first flow line 375. The one or more control orchoke valves 390 can be disposed in the first line 387 to regulate theamount of fluid and/or pressure of the fluid flowing through therecirculation loop 370.

The recirculation loop 370 can be activated by at least partiallyopening one or more control valves 390 to increase and/or regulate flowthrough pump 380 and/or to maintain the temperature of the fluid in thesecond flow line 385 below a maximum design temperature of the system300 or a desired temperature threshold. For example, when one or both ofthe flow meters 378, 383 determine a decrease in the flow rate throughthe pump 380, the control valve 390 can be opened to activate therecirculation loop 370. Once the control valve 390 is open, all or aportion of the fluid via line 385 can be diverted to the recirculationloop 370.

The heat exchanger 100 in the recirculation loop 370 can cool the fluidflowing through the recirculation loop 370. For example, if thetemperature of the pumped fluid in the second flow line 385, asdetermined by the second temperature sensor 381, reaches a secondtemperature that approaches the maximum design temperature or thedesired temperature threshold, the control valve 390 can be opened toallow fluid to flow through the heat exchanger 100 in the recirculationloop 370. In another example, if the temperature of the pumped fluid inthe second flow line 385 reaches the second temperature, the slidingsleeve 120 of the heat exchanger 100 can be opened to allow more coolingelement into the housing 115 of the heat exchanger 100, withoutadjusting the amount of flow through the recirculation loop 370. Themaximum design temperature can be variable based on project and materialdesign requirements. For example, the maximum design temperature canrange from a low of about 3° C., about 10° C., about 50° C., or about100° C. to a high of about 150° C., about 200° C., about 250° C., orabout 300° C. In another example, the maximum design temperature can beabout 175° C. or less.

The temperature sensors 131, 132 in the heat exchanger 100 can measurethe temperature of the fluid going in and out of the heat exchanger 100.The heat exchanger 100 can cool the diverted fluid to a temperatureequal to the first temperature of the fluid in the first flow line 375.For example, if the second temperature measured by the secondtemperature sensor 132 in the second flow line 385 is greater than thefirst temperature measured by the first temperature sensor 131 in thefirst flow line 375, the sliding sleeve 120 of the heat exchanger 100can be adjusted to allow heat transfer medium into the housing 115 ofthe heat exchanger 100, thereby cooling the fluid in the recirculationloop 370 to the first temperature measured in the first flow line 375, atemperature below the first temperature, or a temperature between thefirst temperature and the second temperature measured in the second flowline 385. The sliding sleeve 120 can be automatically adjusted forchanges in temperature and pressure in the flow lines 375 and 385. Forexample, as the temperature sensor 381 measures a temperature increasein the flow line 385, the sliding sleeve 120 of the heat exchanger 100can be actuated to allow more of the heat transfer medium into thehousing 115 and in contact with the coil 110. This can result inincrease heat transfer by conduction, convection, or both. In this way,the first flow rate through the pump 380 can be maintained without adramatic temperature increase in the system 300.

The recirculation loop 370 can provide additional flow to the first flowline 375 to maintain a minimum flow rate in the pump 380. This can allowthe pump 380 to remain in operation if the flow rate in the first flowline 375 drops below the minimum flow rate of the pump 380. Thus, thepump 380 can operate over a large range of flow rates and can lower theacceptable minimum flow rate from a fluid source, e.g., a hydrocarbonfield or well, thereby increasing the operation efficiency of the pump380. For example, with the recirculation loop 370 available, the pump380 can operate at flow rates of about 80% or even 90% of the maximumflow rate of the pump 380. Increasing the operation range of the pump380 can lower capital cost and increase the efficiency of the system300. Increasing the flow rate to the pump 380 can increase theefficiency of the pump 380 by allowing pump operation at idealconditions, i.e., away from modes of operation that produce excessivemechanical stress on components of the pump 380. Maintenance and systemdowntime of the system 300 can be reduced if the pump 380 runs atmaximum efficiency.

Although not shown, a plurality of pumps 380 each having one or morelines 370 can be run in series, in parallel, or a combination thereof totransport hydrocarbons from a source, e.g., a subsea well or productionzone, to a further location, e.g., a surface ship or rig.

FIG. 4 depicts schematic of another illustrative system 400 forcontrolling the temperature of a fluid during transport having two ofthe heat exchangers 100 depicted in FIG. 1 arranged in series withrespect to one another, according to one or more embodiments. Similar tothe system 300 in FIG. 3, the system 400 depicted in FIG. 4 can includeone or more flow lines (two are shown 370, 385), one or more pumps 380,and one or more recirculation loops 470.

The recirculation loop 470 can include two or more heat exchangers twoare shown 100A, 100B) linked in series and one or more control or chokevalves 490. Although two heat exchangers 100A and 100B are shown inseries more heat exchangers can be added in series, in parallel, orboth. The recirculation loop 470 can be formed by a plurality of linesor conduits (three are shown 487, 489, 473). Fluid from the second flowline 385 can be introduced via a first line 487 to a first heatexchanger 100A to produce a first cooled fluid via a second line 489.The first cooled fluid can be introduced via the second line 489 to asecond heat exchanger 100B to produce a second cooled fluid via a thirdline 473. The second cooled fluid via the third line 473 can bereintroduced to the first flow line 375. The control valve 490 can bedisposed in the first line 487 to regulate the amount of fluid flowingthrough the recirculation loop 470.

One or more first temperature sensors 376, one or more first pressuresensors 377, and one or more first flow meters 378 can be disposed onthe first flow line 375 to measure the temperature, pressure, and flowrate of the fluid in the first flow line 375. One or more secondtemperature sensors 381, one or more second pressure sensors 382, andone or more second flow meters 383 can be disposed on the second flowline 385 to measure the temperature, pressure, and flow rate of thepumped fluid in the second flow line 385.

In operation, a fluid. e.g., a hydrocarbon fluid, can be introduced viathe first flow line 375 to the pump 380 to produce a pumped fluid via asecond flow line 385. The pumped fluid via the second flow line 385 canbe transported to an alternate location, including, but not limited to,a production manifold, a boosting station, or the surface (e.g., asurface vessel or rig). The pump 380 can increase the pressure of thefluid introduced from the first flow line 375 to maintain the first flowrate of the fluid or increase the flow rate of the fluid to a secondflow rate in the second flow line 385.

The recirculation loop 470 can be activated by at least partiallyopening the control valve 490 to increase flow through pump 380 and/orto maintain the temperature of the fluid in the second flow line 385below a maximum design temperature of the system 400 or a desiredtemperature threshold. For example, when one or both of the flow meters378, 383 determine a decrease in the flow rate through the pump, thecontrol valve 490 can be opened to activate the recirculation loop 470.All or a portion of the fluid via line 385 can be diverted to therecirculation loop 470.

The heat exchangers 100A, 100B can cooperate to cool the fluid andthereby lower the pressure of the fluid flowing through therecirculation loop 470. For example, if the temperature of the pumpedfluid in the second flow line 385, as determined by the secondtemperature sensor 381, reaches a second temperature that approaches themaximum design temperature or the desired temperature threshold, thecontrol valve 490 can be at least partially opened to allow fluid toflow through the first heat exchanger 100A and then through the secondheat exchanger 100B in the recirculation loop 470. In another example,if the temperature of the pumped fluid in the second flow line 385reaches the second temperature, the sliding sleeves 120 of one or bothof the heat exchangers 100A, 100B can be opened to allow more coolingelement into the housings 115 of the heat exchangers 100A, 100B, withoutadjusting the amount of flow through the recirculation loop 470. Themaximum design temperature can range from a low of about 3° C., about10° C., about 50° C., or about 100° C. to a high of about 150° C., about200° C., about 250° C., or about 300° C. In another example, the maximumdesign temperature can be about 175° C. or less.

Placing the heat exchangers 100A, 100B in series can effectivelyincrease the surface area of the coils 110. For example, in somecircumstances the two or more heat exchangers 100A, 100B in series canbe used instead of a larger heat exchanger 100 having a larger coil 110.Several smaller heat exchangers 100 can lower material and/or transportcosts. For example, large heat exchangers 100 can require largetransport vessels and equipment to place them at the sea floor and/orwellhead, whereas two smaller heat exchangers 100 can be transportedwith a smaller vessel. Several heat exchangers 100 can also improve therobustness of the system 400. For example, if one of the heat exchangers100 should fail or require maintenance, the system 400 can continue viathe bypass line(s) 107 of the inoperative heat exchanger 100.

The temperature sensors 131, 132 in the heat exchangers 100A, 100B canmeasure the temperature of the fluid going in and out of each heatexchanger 100A, 100B. The heat exchangers 100A, 100B can cool thediverted fluid to a temperature equal to the first temperature of thefluid in the first flow line 375, a third temperature below the firsttemperature measured in the first flow line 375, or a fourth temperaturebetween the first temperature measure in the first flow line 375 and thesecond temperature in the second flow line 385. For example, if thesecond temperature measured by the second temperature sensor 132 in thesecond flow line 385 is greater than the first temperature measured bythe first temperature sensor 131 in the first flow line 375, the slidingsleeves 120 of the heat exchangers 100A, 100B can be independentlyadjusted to allow heat transfer medium into the housing 115 of the heatexchangers 100A, 100B, thereby cooling the fluid to the firsttemperature measured in the flow line 375. The sliding sleeves 120 ofthe heat exchangers 100A, 100B can be automatically adjusted for changesin temperature and pressure in the flow lines 375 and 385. For example,as the temperature sensor 381 measures a temperature increase in theflow line 385, the sliding sleeve 120 of one or more of the heatexchangers 100A, 100B can be actuated to allow more of the heat transfermedium into the housing 115 and in contact with the coil 110 of eachheat exchanger 100A, 100B. This can result in increased heat transfer byconduction, convection, or both. In this way, the first flow ratethrough the pump 380 can be maintained without a dramatic temperatureincrease in the system 400.

Like the recirculation loop 370 in the system 300, the recirculationloop 470 can provide additional flow to the first flow line 375 tomaintain a minimum flow rate in the pump 380 for the reasons andadvantages discussed and described above.

FIG. 5 depicts a schematic of yet another illustrative system 500 forcontrolling the temperature of a fluid during transport having two ofthe heat exchangers 100 depicted in FIG. 1 arranged in parallel withrespect to one another, according to one or more embodiments. Similar tothe systems 300 and 400, the system 500 can include one or more flowlines (two are shown 370, 385), one or more pumps 380, and one or morerecirculation loops 570.

The recirculation loop 570 can include two or more heat exchangers (twoare shown 100A, 100C) linked in parallel and one or more control orchoke valves (three are shown 590, 591, 592). Although two heatexchangers 100A and 100C are shown in parallel, more heat exchangers canbe added in series, in parallel, or both. The recirculation loop 570 canbe formed by a plurality of lines or conduits (six are shown 587, 588,589, 571, 572, 573) linking the heat exchangers 100A, 100C, the valves590, 591, 592, and the flow lines 375, 385. Fluid from the second flowline 385 can be introduced via a first line 587 and a second line 588 tothe first heat exchanger 100A to produce a first cooled fluid via athird line 571. Fluid from the second flow line 385 can be introducedvia the first line 587 and a fourth line 589 to a second heat exchanger100C to produce a second cooled fluid via a fifth line 572. The thirdand fifth lines 571 and 572 can feed into a sixth line 573, and thefirst cooled fluid, the second cooled fluid, or a mixture of both can bereintroduced via the sixth line 573 to the first flow line 375.

A first control valve 590 can be disposed in the first line 587 toregulate the amount of fluid flowing through the recirculation loop 570.A second control valve 591 can be disposed in the second line 588 andcan regulate the amount of fluid flowing to and/or cooled by the firstheat exchanger 100A. A third control valve 592 can be disposed in thesecond line 588 and can regulate the amount of fluid flowing to and/orcooled by the second heat exchanger 100C.

Although not shown, control lines can link control valves 590, 591, 592to a control unit (not shown). The control unit can be disposed on thesurface (e.g., a ship or a rig), proximate the pump 380 and therecirculation loop 570, at another location, or at a combinationthereof. In another example, the control valves 590, 591, 592 can bewirelessly linked to the control unit.

As discussed and described above, the first temperature sensor 376, thefirst pressure sensor 377, and the first flow meter 378 can be disposedon the first flow line 375 to measure the temperature, pressure, andflow rate of the fluid in the first flow line 375. The secondtemperature sensor 381, the second pressure sensor 382, and the secondflow meter 383 can be disposed on the second flow line 385 to measurethe temperature, pressure, and flow rate of the pumped fluid in thesecond flow line 385.

In operation, a fluid, e.g., a hydrocarbon fluid, can be introduced viathe first flow line 375 to the pump 380 to produce the pumped fluid viathe second flow line 385. The pumped fluid via the second flow line 385can be transported to an alternate location, including, but not limitedto, a production manifold, a boosting station, or the surface (e.g., asurface vessel or rig). As in the systems 300 and 400, the pump 380 canincrease the pressure of the fluid introduced from the first flow line375 to maintain the first flow rate of the fluid or increase the flowrate of the fluid to a second flow rate in the second flow line 385. Thefirst temperature, first pressure, and first flow rate in the first flowline 375 and the second flow rate in the second flow line 385 can be thesame or similar to those discussed and described above.

The recirculation loop 570 can be activated by at least partiallyopening the control valve 590 and one or more of the second and thirdcontrol valves 591, 592 to increase flow through pump 380 and/or tomaintain the temperature of the fluid in the second flow line 385 belowa maximum design temperature of the system 500. For example, the thirdcontrol valve 592 can be closed to completely block the flow of fluid tothe fourth line 589 and the second heat exchanger 100C, thereby allowingfluid to only be cooled by the first heat exchanger 100A. In anotherexample, the second control valve 591 can be closed to completely blockthe flow of fluid to the second line 588 and the first heat exchanger100A, thereby allowing fluid to only be cooled by the second heatexchanger 100C. In yet another example, the second control valve 591 andthe third control valve 592 can both be opened to allow fluid throughboth heat exchangers 100A and 100C. All or a portion of the fluid vialine 385 can be diverted to the recirculation loop 570.

The heat exchangers 100A, 100C can work independently or cooperate tocool the fluid and thereby lower the pressure of the fluid flowingthrough the recirculation loop 570. For example, as the temperature ofthe pumped fluid in the second flow line 385, as determined by thesecond temperature sensor 381, reaches a second temperature thatapproaches the maximum design temperature or a desired temperaturethreshold, the first control valve 590 and the second control valve 591can be at least partially opened to allow fluid to flow through thefirst heat exchanger 100A. If further cooling is desired, the thirdcontrol valve 592 can be at least partially opened to allow fluid toflow through the second heat exchanger 100C. In another example, if thetemperature of the pumped fluid in the second flow line 385 reaches thesecond temperature, the sliding sleeves 120 of one or both of the heatexchangers 100A, 100C can be opened to allow more cooling element intothe housings 115 of the heat exchangers 100A, 100C, without adjustingthe amount of flow through the recirculation loop 570. The maximumdesign temperature can range from a low of about 3° C. about 10° C.,about 50° C., or about 100° C. to a high of about 150° C. about 200° C.,about 250° C., or about 300° C. For example, the maximum designtemperature can be about 175° C. or less.

Placing the heat exchangers 100A, 100C in parallel can effectivelyincrease the surface area of the coils 110. For example, the two or moreheat exchangers 100A, 100C in parallel can be used instead of a largerheat exchanger 100 having a larger coil 110. Placing the heat exchangers100A, 100C in parallel with the control valves 590, 591, 592 can allowflexible adjustment of the effective surface area of the coil 110 byactivating one or more of the heat exchangers 100A, 100C.

The temperature sensors 131, 132 in the heat exchangers 100A, 100C canmeasure the temperature of the fluid going in and out of each heatexchanger 100A, 100C. The heat exchangers 100A. 100C can cool thediverted fluid to a temperature equal to the first temperature of thefluid in the first flow line 375. For example, if the second temperaturemeasured by the second temperature sensor 132 in the second flow line385 is greater than the first temperature measured by the firsttemperature sensor 131 in the first flow line 375, the sliding sleeves120 of the heat exchangers 100A, 100C can be adjusted to allow heattransfer medium into the housing 115 of the heat exchangers 100A, 100C,thereby cooling the fluid via the sixth line 573 to the firsttemperature in the flow line 375. The sliding sleeves 120 of the heatexchangers 100A, 100C can be automatically adjusted for changes intemperature and pressure in the flow lines 375 and 385. For example, ifthe temperature sensor 381 measures a temperature increase in the flowline 385, the sliding sleeve 120 of one or more of the heat exchangers100A, 100C can be actuated to allow more of the heat transfer mediuminto the housing 115 and in contact with the coil 110 of each heatexchanger 100A, 100C. This can result in increased heat transfer byconduction, convection, or both. In this way, the first flow ratethrough the pump 380 can be maintained without a dramatic temperatureincrease in the system 500.

The recirculation loop 570 can provide additional flow to the first flowline 375 to maintain a minimum flow rate in the pump 380 for the reasonsand advantages discussed and described above.

Embodiments of the present disclosure further relate to any one or moreof the following paragraphs:

1. A method for transporting a hydrocarbon comprising introducing afluid at a first pressure and a first temperature to an inlet of a pump;pressurizing the fluid within the pump to produce a pressurized fluidhaving a second pressure and a second temperature; and flowing at leasta portion of the pressurized fluid through a first heat exchanger andback to the inlet of the pump, wherein the heat exchanger comprises: acoil having an inlet and an outlet; a housing at least partiallyenclosing the coil and having a first opening and a second opening,wherein a first end of the coil is disposed proximate the first opening;and a foundation for supporting the coil and the housing.

2. The method of paragraph 1, wherein flowing the at least a portion ofthe pressurized fluid through the first heat exchanger cools the atleast a portion of the pressurized fluid.

3. The method of paragraph 2, wherein the at least a portion of thepressurized fluid flows through one or more valves to produce adepressurized fluid prior to flowing the at least a portion of thepressurized fluid through the first heat exchanger.

4. The method according to any one of paragraphs 1 to 3, furthercomprising flowing the at least a portion of the pressurized fluidthrough the first heat exchanger, a second heat exchanger, and back tothe inlet of the pump.

5. The method of paragraph 4, wherein the second heat exchanger isarranged in series with the first heat exchanger.

6. The method of paragraph 4 or 5, wherein the second heat exchanger isarranged in parallel with the first heat exchanger.

7. The method according to any one of paragraphs 1 to 6, furthercomprising sensing at least one of a pressure, a temperature, and a flowrate of the pressurized fluid; and adjusting an amount of thepressurized fluid flowing through the first heat exchanger based on atleast one of the sensed pressure, temperature, and flow rate.

8. A system for transporting a hydrocarbon, comprising a pump having aninlet and an outlet; a recirculation loop joined to the outlet of thepump at a first end of the recirculation loop and joined to the inlet ofthe pump at a second end of the recirculation loop, the recirculationloop comprising: a heat exchanger; and a control valve disposed betweenthe first end of the loop and the heat exchanger.

9. The system of paragraph 8, wherein the heat exchanger comprises: acoil having a fluid inlet and a fluid outlet; a housing at leastpartially enclosing the coil and having a first and a second opening,wherein a first end of the coil is disposed proximate the first opening;and a foundation for supporting the coil and the housing.

10. The system of paragraph 8 to 9, further comprising one or more firsttemperature sensors, one or more first pressure sensors, one or morefirst flow meters, or any combination therefore, wherein the one or morefirst temperature sensors, one or more first pressure sensors, and oneor more first flow meters are each disposed proximate the inlet of thepump.

11. The system of claim 10, further comprising one or more secondtemperature sensors, one or more second pressure sensors, one or moresecond flow meters or any combination thereof, wherein the one or moresecond temperature sensors, one or more second pressure sensors, and oneor more second flow meters are each disposed proximate the outlet of thepump.

12. An apparatus for exchanging heat between a fluid and a heat transfermedium, comprising: a coil having an inlet and an outlet; a housing atleast partially enclosing the coil and having a first opening and asecond opening, wherein a first end of the coil is disposed proximatethe first opening; and a foundation for supporting the coil and thehousing.

13. The apparatus of paragraph 12, wherein the housing comprises asliding sleeve adapted to adjust a size of the first opening.

14. The apparatus of paragraph 13, further comprising a second slidingsleeve disposed proximate the second opening and adapted to adjust adistance between a second end of the coil and the second opening.

15. The apparatus according to any one of paragraphs 12 to 14, whereinthe housing comprises a frame and a sidewall.

16. The apparatus of paragraph 15, wherein the frame protrudes from thesecond opening of the housing and has a ring aligned along alongitudinal axis extending through the second opening.

17. The apparatus of paragraph 15 or 16, wherein the sidewall has one ormore maintenance ports.

18. The apparatus according to any one of paragraphs 12 to 17, furthercomprising a flow meter disposed at the hydrocarbon inlet.

19. The apparatus according to any one of paragraphs 12 to 18, whereinthe coil is at least partially coated with one or more anti-foulingagents.

20. The apparatus according to any one of paragraphs 12 to 19, whereinthe coil is at least partially coated with one or more anti-foulingagents.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges from any lower limit to any upper limit arecontemplated unless otherwise indicated. Certain lower limits, upperlimits, and ranges appear in one or more claims below. All numericalvalues are “about” or “approximately” the indicated value, and take intoaccount experimental error and variations that would be expected by aperson having ordinary skill in the art.

Various terms have been defined above. To the extent a term used in aclaim is not defined above, it should be given the broadest definitionpersons in the pertinent art have given that term as reflected in atleast one printed publication or issued patent. Furthermore, allpatents, test procedures, and other documents cited in this applicationare fully incorporated by reference to the extent such disclosure is notinconsistent with this application and for all jurisdictions in whichsuch incorporation is permitted.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A system for transporting a hydrocarbon at asubsea location, comprising: a pump having an inlet and an outlet, theinlet receiving the hydrocarbon produced from a well; and arecirculation loop having: a first end joined to the outlet of the pump;a second end joined to the inlet of the pump; and a heat exchanger atleast partially submerged in a heat transfer medium and receiving only,a portion of the hydrocarbon flowing from the pump, wherein the heatexchanger includes: a coil having a fluid inlet and a fluid outlet, anda housing at least partially enclosing the coil and having a first and asecond opening, wherein a first end of the coil is disposed proximate tothe first opening, and wherein the housing comprises a sliding sleeveconfigured to adjust a size of the first opening and a second slidingsleeve disposed proximate the second opening and configured to adjust adistance between a second end of the coil and the second opening.
 2. Thesystem of claim 1, wherein the heat exchanger further comprises afoundation for supporting the coil and the housing.
 3. The system ofclaim 1, further comprising one or more first temperature sensors, oneor more first pressure sensors, or one or more first flow metersdisposed proximate the inlet of the pump.
 4. The system of claim 3,further comprising one or more second temperature sensors, one or moresecond pressure sensors, or one or more second flow meters disposedproximate the outlet of the pump.
 5. The apparatus of claim 1, whereinthe housing comprises a frame and a sidewall.
 6. The apparatus of claim5, wherein the frame protrudes from the second opening of the housingand has a ring aligned along a longitudinal axis extending through thesecond opening.
 7. The apparatus of claim 6, wherein the sidewall hasone or more maintenance ports.
 8. The apparatus of claim 1, furthercomprising a flow meter disposed at e coil inlet.
 9. The apparatus ofclaim 1, wherein the coil is at least partially coated with one or moreanti-fouling agents.
 10. The apparatus of claim 1, wherein the heattransfer medium is selected from one of: (i) water, and (ii) seawater.